LEDs have recently been attracting attention and widely used as a light source in a lighting device mounted on a dental handpiece for their lower electric power consumption and longer service life compared to conventional halogen lamps. JP-10-137263-A discloses a light-emitting device which includes an LED enclosed in a translucent cover, and electrode terminals electrically connected to and linearly extending from the LED, and is in a compact size as a whole suitable for installation in a dental handpiece. The translucent cover enclosing the LED is in the form of a bullet, out of which the two linear terminals (anode and cathode terminals) connected to the LED extend. The light-emitting device is installed in a dental handpiece with the two linear terminals being connected to the connecting terminals of a lighting device arranged in a coupling connecting a handpiece body and a hose. In the installed state, the light-emitting device is arranged facing to the light-receiving surface of the optical fibers disposed in the handpiece body to introduce light emitted from the LED into the optical fibers.
However, in such a conventional light-emitting device, the two electrode terminals are made of the same linear materials, so that the polarity is hard to be distinguished. This may cause connection in wrong polarity of the electrode terminals to the corresponding connecting terminals of a lighting device.
Further, the linearity of the electrode terminals does not allow sufficient heat release for protection of the LED.
In addition, the linear electrode terminals require a certain space between the terminals as well as around each terminal, which obstruct downsizing of the overall light-emitting device.